Shock absorber



Oct. 5,'1937. J, |l WALLACE v 2,095,112

SHOCK ABSORBER Original Filed Nov. 2, 1933 y INVENTORI. HG. j` /bHNFMLLACE Mil/gam @ZM ATTORNEY5 Patented Oct. 5, 1937 UNITED STATES PATENTGFFICE SHOCK ABSORBER Original application November 2, 1933, Serial No.696,468. Divided and this application May 4,

1935, Serial No. 19,852

6 Claims.

'I'his invention relates to improvements in shock absorbers. It isdesigned primarily for use upon airplanes to cushion the impact oflanding and to absorb the shocks of taxying.

The present application is a division of my copending application,Serial. No. 696,408, led November 2, 1933.

One of the objects of the invention is the provision of novel means forregulating the ow of liquid through metering openings in such manner asto automatically adjust the rate of i'low to the load at any giveninstant, thereby making the operation of the device suliciently flexibleto t all conditions.

Another object is the provision of novel valve means for varying therate of flow of liquid through a piston or other partition employed inshock absorbers having hydraulic action.

Still another object is the provision of a shock absorber havinghydraulic action with automatic ilow rate adjustment, the latter beingcarried exclusively by the piston of the strut.

Other objects and features of novelty Will appear as I proceed with thedescription of those embodiments of the invention which, for thepurposes of the present application, I have illustrated in theaccompanying drawing, in which Fig. 1 is an elevational View, partly incentral longitudinal section, of an airplane strut embodying theinvention.

Fig. 2 is a cross sectional view of the same taken substantially on theline 2-2 of Fig. 1, and

Figs. 3 and 4 are sectional detailed views of modified forms ofself-adjusting liquid metering valves.

In Fig. 1 I have shown my invention applied to an airplane strut inwhich the usual arrangement of the cylinders is inverted the outercylinder in this case being the lower cylinder and the inner cylinderbeing the upper cylinder. This is a desirable arrangement where thelength of the strut must be restricted on account of the design of theairplane upon which the strut is to be used. While the Apresentinvention is peculiarly suited to a strut of this character, it is to beunderstood that its application is not limited in this respect,

The construction includes an outer lower cylinder 42 and an inner uppercylinder 43. The outer end of the lower cylinder is closed by a cap 44which is threaded into the end of that cylinder yand carries a pair ofring brackets 45 to which is fastened a wheel spindle 46. The innercylinder 43 has a cap 41 at its outer end, which may be Welded to thecylinder, and carries a bracket 48 for attachment to the airplane.

The outer cylinder is formed with an enlargement at its inner end, inwhich there is a pocket 49. Within the latter I mount a packing 50 of vacharacter such that it will expand laterally when subjected to pressureaxially of the strut. For a more particular description of this packing,reference may be had to my Patent No. 1,888,578, issued November 22,1932. At the inner end this packing is engaged by a metal ring which isfree to move in pocket 49, While at its outer end the packing is engagedby a gland ring 52 threaded into the end of the cylinder.

The packing 50 bears against the smooth outer surface of the cylinder43. At the lower end of the latter cylinder however there is a head 25',in the outer `surface of which are cut splines 21' which are interttedwith splines 28' formed on the inner surface of cylinder 4.2 andextending from the pocket 49 to the cap 44. These interengaging splinesprevent swiveling.

In the head 25' I mount, preferably by a threaded connection, a piston14B. The piston is provided with continuously open holes 53 of smallsize and a central opening 54 of larger size. Around this centralopening there is an upwardly extending annular fiange 55 upon which isthreaded a small cylinder 56 which is closed at its upper end except fora. central port 51, and is provided with a plurality of ports 58 in itsside walls directly above the flange 55. The port 51 is normally closedby a spring controlled valve plate 59, in which there is a small centralopening 6|).

Within the cylinder 56 there is a piston 6| which is closely fitted tothe cylinder and carries centrally a depending tapered metering pin 62.

When the strut is at rest, the piston 6| is in its lowermost position,closing off ports 58. When a small shock is encountered, liquid flowsthrough the holes 53, and the piston 6| may rise slightly to permit someflow through opening 54 and the partially open ports 58. On the rebound,liquid enters the space within the cylinder 56 through port 51, theplate 59 being unseated. The piston 6| is thereby forced down to itslowermost position, and the metering of liquid must take placeexclusively through the holes 53, thereby checking the rebound.

When the strut receives a heavy impact, the liquid pressure beneath thepiston 6| and against the lower end of pin 62 expels the liquid abovethe piston through the small hole 60, as rapidly as the small size ofthat hole will permit, thereby uncovering more or less of the ports 58in order that flow through the piston may take place at a faster rateand in order that some of the im" pact may be absorbed by the highlyresilient lair in the upper end of the strut. When the impact isparticularly heavy the piston 6| may rise high enough in the cylinder 56to bring the larger lower end of pin 62 into the opening 54, therebyretarding the iiow.

It will be appreciated that this valve may be employed with or withoutthe metering pin. Its action is hydraulically controlled except as it isaffected by the springs controlling plate 59.

Its operation may be varied bychanges in the size of,k the hole 88 aswell as by changes in the size or number of holes 53.

The valve units illustrated in Figs. 3 and 4 may be substituted for thatof Fig. 1, if desired.

In Fig. 3 the plate I4D has no opening therethrough except the centralconical opening 10. To the plate around this opening`\` there is securedby any suitable means a sleeve or cylinder 1| having side ports 12.Within this sleeve there is a conical valve piece 13 on the lower end ofa stem 14, the valve piece and stem being drilled axially to form acentral continuously open passage 15. A coil spring 18 surrounds thestem 14 and presses at its lower end against the valve piece 13 and atits upper end against a collar 11 which is threaded into the sleeve andhas a smooth bore by means of which the stem 14 is guided. The tensionof the spring may be varied by adjustmentof the collar 11. i

On the compression stroke liquid flows through passage 15. If pressureconditions are such however that the rate of flow permitted by thissmall passage is insumcient, then the valve piece will rise, compressingspring 1S, permitting flow` around the valve piece into the cylinder 1land out through the ports 12. It may be noted however that When thevalve piece 13y is lifted off its seat the eiective area exposed to thepressure beneath the piston is increased, and the closing of the valveby the spring 16 is correspondingly delayed. Variations in operation areaccomplished by the adjustment of the collar 11.

'Ihe form of valve illustrated in Fig. 4 is quite similar to that ofFig. l. The plate |4E is provided with small openings 18 like Atheopenings 53 of Fig. 1. It also has an annular flange 19 on which isthreaded a cylinder 80 in which slides a piston 8| supporting a meteringpin 82 which extends through a central opening 83 in the plate I4E.

The cylinder has side ports 84 and an end port 85. The operation of thisdevice is quite similar to that of Fig. 1. On the rebound, liquid canenter the space within the cylinder 80 above the piston 8| somewhat moreslowly than through port 51 with the valve plate 59 unseated. On theimpact stroke, the piston 8| rises at a rate of speed more or less inproportiomto the force of the impact, except that the size of the streamspeed of now, in accordance with a well known law of hydraulics, that isto say, if the speed 01El flow is moderate, the. quantity of liquidpassing through the oriilce at any given instant is greater than it lswhen the speed is considerably increased.

Variations from the described structures may be employed. Accordingly, Idesire it to be understood that the scope of the invention is to beregarded as'deiined exclusively by kthe appended claims rather than bythe foregoing description r the accompanying illustrations.

Having thus described my invention, I claim:

l. In a shock absorber, two telescoping members adapted to be interposedbetween the parts whose relative movements are to be cushioned, apartition i'lxed with respect to one of said members having a liquidmetering passage extending centrally therethrough, an upwardlyextendingcylinder mounted on said partition surrounding said passage, and meansfor progressively changing the size of said passage as' the pressureWithin the shock absorber increases or decreases, comprising a meteringpin cooperating with said passage and extending upwardly into saidcylinder, said pin being mounted in the cylinder, and means in thecylinder permitting' movement of the pin in response to variations influid pressure within the shock absorber.

2. Ina shock absorber, two telescoping members adapted to be interposedbetween the parts whose relative movements are to be cushioned, apartition fixed with respect to one of said members having a liquidmetering passage therethrough, and means for progressively changing thesize of said passage as the pressure Vwithin the shock absorberincreases or decreases, saidv means being carried exclusively by saidpartition and being actuated in both directions exclusively by uidpressure within the shock absorber.

3. In a shock absorber, two telescoping members adapted to be interposedbetween the parts whose relative movements are to be cushioned, apartition fixed with respect to one of said members having a liquidmetering passage therethrough, a cylinder carried by said partitionconcentric with said passage,.said cylinder having a port therethrough,and means movable lengthwise of said cylinder and responsive topressures within the shocky absorber for varying the effective size of.said port.

4. In a shock absorber, two telescoping members adapted to be interposedbetween the parts whose relative movements are to be cushioned, apartition fixed with respect to one of said members having a liquidmetering passage extending centrally therethrough, a cylinder carried bysaid partition concentric with said passage, and spaced from thesurrounding walls of the shock absorber, the free end of the cylinderbeing provided with an opening, a piston slidable in said cylinder, anda metering pin carried by the piston and extending through said meteringpassage.

5. In a shock absorber, two telescoping members adapted to `beinterposed between the parts whose relative movements are to becushioned, a partition xed with respect to one of said members having aliquid metering passage therethrough, a cylinder carried by saidpartition concentric with said opening, the free end of the cylinderbeing provided with an opening, a piston slidable in said cylinder, anda metering pin carried by the piston and extending through said meteringpassage, said cylinder having a port in its side wall adapted to beclosed or opened by said piston.

6. In a shock absorber, two telescoping members adapted to be interposedbetween the parts whose relative movements are to be cushioned, a

partition ilxed with respect to one of said members having a liquid"metering passage therethrough, a cylinder carried by said partitionconcentric with said passage, a valve in the free end of the cylindernormally springclosed and adapt- .ed .to open by liquid pressure duringthe expanding .strokeof the shock absorber, a piston slid.- able in saidcylinder, and a metering pin carried by the piston and extending throughsaid metering passage. A

JOI-IN F. WALLACE.

